1. Technical Field
The present invention relates to a vehicle, and more particularly to a vehicle in which an airbag is installed in a seat back of a front seat, from among seats disposed on front and rear sides.
2. Related Art
In a conventional vehicle such as an automobile, a seat occupant is protected from an impact generated during a collision by deploying/inflating an airbag disposed in a seat back of a vehicle seat.
In a vehicle seat disclosed in Japanese Unexamined Patent Application Publication (JP-A) No. H10-273000, for example, a seat pad is provided on a front surface of a suspended elastic support member suspended within a seat back frame, and an airbag is disposed in a deflated condition within a gap between the suspended elastic support member and a rigidly structured support plate disposed behind the suspended elastic support member.
According to this vehicle seat, the airbag is inflated between the suspended elastic support member and the support plate by an action of an inflator following detection of at least a predetermined impact load. As a result, rearward movement of the seat occupant during a collision is supported elastically, and thereby restricted, from behind, while an impact energy generated by the collision is absorbed through depressurization and deflation of the airbag.
Further, in an airbag device disclosed in JP-A No. 2010-052621, a first airbag that is deployed so as to inflate toward a seat occupant of a rear seat is disposed in a back surface lower portion of a seat back of a front seat, and a second airbag is disposed in a flattened condition on a front surface of a suspended elastic support member suspended within a seat back frame of the seat back of the front seat.
According to this airbag device, the first airbag is deployed so as to inflate toward the seat occupant of the rear seat by an action of an inflator following detection of at least a predetermined impact such that even when the seat occupant of the rear seat is moved forward by an impact generated during a collision, the seat occupant is prevented from forcefully striking a back surface of the seat back of the front seat. Further, by deploying/inflating the second airbag, rearward movement of an upper body of a seat occupant of the front seat during the collision is elastically supported, and thereby restricted, from behind, and as a result, the seat occupant is protected. Furthermore, by controlling respective inflation timings of the first and second airbags, the seated passengers are protected appropriately.
As described above, however, in the vehicle seat disclosed in JP-A No. H10-273000, the seat occupant of the seat is protected by the airbag and the existence of the rigidly configured support plate behind and on an outer side of the airbag. In other words, an impact generated by rearward movement of the seat occupant is alleviated by the airbag, while an impact applied from the rear of the seat back is first received by the support plate and then absorbed by the airbag.
Therefore, when, for example, a seat exists behind the seat and the rear seat is occupied, and the rear seat occupant collides with the seat back of the front seat from behind, a large impact is generated upon collision with the support plate. Hence, the impact from the rear cannot be received softly, and as a result, knees and so on of the rear seat occupant may be damaged, and the front seat occupant may also receive a large impact.
According to the airbag device of JP-A No. 2010-052621, on the other hand, protection and damage reduction in relation to the seat occupant of the front seat can be expected from the second airbag that is deployed so as to inflate within the seat back of the front seat, and since the first airbag is deployed so as to inflate toward the rear seat occupant side, the rear seat occupant is also protected. However, the first airbag that is deployed so as to inflate rearward and outward from the seat back must be provided separately in the lower portion of the seat back of the front seat in addition to the airbag disposed in the seat back, leading to increases in the structural complexity of the seat back and a control load exerted on the respective airbags.
Further, the first airbag swells diagonally upward by a large amount from the back surface lower portion of the seat back of the front seat toward the occupant of the rear seat, and therefore an inflating deployment shape thereof is unstable. Stability may therefore be lacking with respect to accurate and reliable reception of a collision between the seat occupant of the rear seat and the seat back of the front seat, and absorption of the resulting impact.
Hence, in the respective structures of the conventional patent documents described above, there remains room for improvement in terms of protecting a seat occupant of a front seat directly using an airbag and protecting the front seat occupant from an impact on the seat back from behind using a simple structure.
Note that in a vehicle such as an automobile, a collision between the knees and so on of the rear seat occupant and the seat back of the front seat, such as that described above, may occur not only during a collision from the front, but also in a situation where a collision occurs from the rear such that a vehicle body rear portion deforms or the like, causing the rear seat occupant to be pushed forward such that his or her knees forcefully strike the back surface of the seat back of the front seat.